Gas generator



Feb. 2-0, 1951 J. A. HANNUM 2,54%194 GAS GENERATOR Filed June 14, 1947 sshee'ts-sheet-z INVENTOR. BY JOHN A. HANNUM ATTORNEYS' ffatenteci 20,195i GAS GENERATOR John A. Hannum, Detroit, Mich., assignor, by

mesne assignments, to Borg-Warner Corporation, Chicago, Ill., acorporation of Illinois Application June 14, 1947, Serial No. 754,788

This invention relates to a method and appa-` ratus for producing gasunder pressure by conned combusticn of a fuel and oxidant and moreparticularly to the conversion of a small volume of a liquid ofrelatively high specific gravity into a large volume of permanent orsemi-permanent gas of low specific gravity.

Apparatus constructed in accord with this invention performs the sameultimate function as an ordinary gas compressor that employs a rotor,reciprocating piston or the like to receive gas at low pressure,compress it and transmit it at a higher pressure. Such compressorsrequire numerous moving parts that must nt closely with each other toavoid gas leakage and that must be replaced from time to time as theywear during use. Furthermore considerable amounts of power are requiredto drive the moving parts, particularly when the gas is to be compressedto high pressures and the presence of the moving parts results in noiseand vibration.

A general object of the present invention is to provide an improvedmethod and apparatus for producing a compressible fluid, includingsteam, at high pressure. Another object is to decompose under controlledconditions a liquid with a relatively high speciiic gravity into arelatively large volume of gas under pressure. A further object is toprovide a method and apparatus for producfl ing a compressible iiuidunder conditions where quietness of operation and freedom from vibrationof the apparatus is essential. Still a further object is to supply fueland oxidant in continuous streams to be burned in a confined combustionchamber to produce elastic iiuids under pressure.

An additional object is to provide apparatus by which fuel and oxidantfed as nongaseous material in the required proportions are mixed andignited in a continuous reaction to decompose to gases. Still a furtherobject of the invention is to provide an apparatus as indicated that maybe conveniently cooled and from which condensate accumulating within thecombustion chamber may readily be removed during operation withoutappreciable loss of pressure in the chamber. Other objects of theinvention include the provision of apparatus that is automaticallycontrolled in its operation to feed the required amounts of fuel andoxidant to the nozzle and to afford continuous operation with safetyagainst excess pressures that may be built up as combustion of the fueland oxidant proceeds.

Further objects of the invention will become apparent from the followingspecification when read with reference to the accompanying drawings. Thenovel features of the invention are summarized in the claims.

Referring now to the drawings: Figure 1 is a vertical transverse sectionthrough a combustion apparatus embodying the present invention; Figure 2is a section through Figure 1 as indicated by the lines 2-2 thereon andFigure 3 is a vertical transverse section through a modified form ofapparatus embodying the present invention.

The apparatus by Which the present invention is practiced is preferablyprovided in one of the forms shown in the drawings and in the first caseincludes as a central component a combustion unit IS in the form of ametal casting. The casting is cored to provide a cooling jacket I2 oversubstantially its entire surface through which cooling water or the likemay be circulated continuously. The Water is admitted through a ttingconnected at I4 and after it has circulated through the jacket isremoved at a similar fitting placed as desired to accomplish mostefficient coolant flow over the entire surface of the combustionchamber.

The combustion chamber is indicated :at I5 and is bounded over itsentire surface by top and bottom walls Il and I8, end walls I9 and 2)and side walls 2| and 22 of the casting. This chamber includes two,although more or less may be provided, hollow transverse Webs 24 and 25that act as radiation shields or bailies between the outlet and themajor combustion region Within the chamber. Each web is cored asindicated at 26 and the hollow portion thereof opens into the coolingjacket I2 where the transverse webs merge with the side walls 2| and 22at 3@ as shown in Figure 2. The web 24 is closed at the center of thebottom to provide a drain passage 32 for purposes hereafter describedand opens into the jacket I2 through the bottom I8 on each side of thepassage 32 in the same manner as indicated at 3D in connection with theside Walls. The web 25 is open at the top as indicated at 311 in. Figurel to communicate with the interior of the jacket I2 through the top wallI'I. It will be evident that coolant circulated through the jacket I2also cools the Webs 24 and 25 to maintain them at the desired operatingtemperature.

In order that the webs may properly act as radiation shields or baiesthey are so arranged that gas traveling from the left-hand side of thecombustion chamber (Figure l) must travel a circuitous path over web 24and under web 25 as indicated by the dotted arrow to reach the outlet.This passes the gases in contact with appreciable cooling surface andeffectively prevents heat due to the high temperatures at the point ofcombustion from traveling across the combustion chamber to the outlet. yy

In order to permit access to the jacket l2 and the Vhollow webs, bothfor the removal of core sand after the casting is poured and also formaintenance purposes during its life a plate 36 is provided bolted as at3l to the top and a similar plate 38 is provided bolted at 39 to theside. The unit may be bolted to a suitable foundation by bolts passingthrough lugs 4U as shown in Figure 2.

The material that is burned within the central portion of the combustionchamber preferably consists of nitromethane as a fuel -afndtetranitromethane as an oxidizing4 agent supplied tovided by means ofthe mechanism indicated at 'il which is connected through leads 19 withthe leads 65 of the burner 59. Since this control mechanism operates ina well-known manner it will not be described in detail. As stated abovethe burner 5S includes electric control valves by which the supply ofeither or both fuel and oxidant may be cut off. If the pressure of thegas passing through the control mechanism 'Il fails below apredetermined value current travels tnrough the leads 'F9 into theburner El] at 65 to open the required valves and supply more of 'eitheror both fuel and oxidant. On the other hand if theV pressure within thecontrol mechanism ll rises beyond a predetermined point the supply offuel and oxidant is in like manner decreased. There is thus provided anautomatic the point of combustion in stoichiometric pro- 1 portions thatburn to end products of 'carbon dioxide, water and free nitrogen. Tosupply these materials two 'conventional gear pumps te and are provided,the one to pump nitromethane and the other t'o `pump tetranitromethanefrom separate suitable storage tanks. The pump i5 pumps through piping1S and a valve i9 to `discharge into a burner 5S as shown in Figure l.and the pump ri pumps through piping '52 and a valve 53 also to`discharge into the burner '5b.

In the burner the two materials are brought together at a suitablemixing nozzle 55 and dis-` provided with a nose 69 that is 4threadedlyreceived in acorresponding opening of the unit it and is secured tightlyin place therein. Two sets vof leads indicated at 6G and '85 areprovided, the 'formerto'supply'current for the operation of 'the"ignite'r 'and thelatter to operate electric control valves to'controlthe supply from the pumps and d5 in accord withthe pressure at theoutlet of ythe combustion chamber as hereafter described.

The fuel and oxidant that aredischarged from 'the Ynozzle are burned inthe enlarged part of 'the combustion'chamber l5 between the end wallltand the transverse web 24 and the volume of gas generated thereby llsthe entire chamber "l5, circulating past the webs and ultimately passingoutof the chamber due to the pressure created by the continuouscombustion of the fuel and oxidant supplied. The products of combustionleave'thechamber at a threaded opening 'le in which is secured a pipetting l2. The fitting in turn communicates with a pressure safety`relief valve l, a hand valve 15 and a 'pressureoperated control box'Hall of conventional construction. After passing through these devicesthe gas continues through piping 'i8 to its place of use or to a storagetank.

The safety valve "itl functions quickly to relieve the pressure withinthe combustion chamber if it builds up beyond va safe value. The

hand valve l5 may be closed as desired to cutl off the ilow of gasbetween the combustion chamber and the piping 18.

Automatic control vof the burning cycle is prothrottlin'g means tocontrol automatically in accord with a predetermined pressure to bemaintained at the outlet "i8 that proper amount of fuel andoxidant-necessary at the nozzle 55. A

Due to the cooling action of the jacket i2 and the-fact that water isnormally one of the end products of the yreaction taking place in thecombustion chamber Va lcertain amount of Icondensate will accumulatetherein. This condensate gradually increases to a point where it coversthe bottom l of the chamber I5', being free to pass from one side of theweb 24 to the other through the opening 32. From time to time thiscondensate may be removed from the system without substantiallyVdecreasing the pressure therein by use of the mechanism now' to bedescribed. A tank with a gauge glass t2 toindicate liquid level isconnected through piping te `into a threadedopening communicating withythe interior of the combustion chamber. A hand valve 3c permits thisAline to be -closedas desired. vln like manner piping 38 leads .from thetank 8F21 vthrough ahand valve VlBEI to piping Si) that dischargesintofa dra-in. The tank B and the piping 84 are strong enough towithstand pressures as great as any Yreached within `the combustionchamber I5.

AInoperation the valve 85 -is normally closed and-the valve te is openedwhen it is desired to drain liquid into the tank te and empty -the com'-bustion chamber. rlhe volume of the tank :is so small -in relation-tothe volume of `the chamber l i5 that there is -no appreciablepressure-drop'sin this latter valve `isagain closed. The operation mayberepeated when needed.

"A modified A--form of apparatus embodying the .present "invention isillustratedin'l'igure, that figure being a transverse vertical sectionthrough a cylindrical apparatus constructed -of sh-eetor plate materialwelded together as hereafter'de- 'scribedI and, among other ways,differing fromthe apparatus previously described in that `the fuel andoxidantarenot supplied separatelyas-componente of 'a -bi-fuel but-as atrue mono-fuel stored in a reservoirfformed inthe apparatus.

"Referring now to Figure 3 `the Y`apparatus -is ,generallyindicated atlili] and comprises acylindrical'sheet metal and welded tank H32 dividedinto a fuel reservoir it, a combustion chamber -I B4 and a `coolingjacket m5. rIhe Ycombustion Achamber `is openjat -the'topandinoperationis closed by anremovablecap ortop H0 thatis alsov,providedwith a cooling jacket.

.i The reservoir 03gis formed 'Within itheside wall |02 between a bottomplate I2 and a bulk; head ||4 extending across the tank and welded tothe side wall. A second bulkhead ||6, spaced above the :rst, provides varegion between the reservoir and combustion-chamber for the circulationof coolant so that high temperaturesdeveloped in the combustion chamberdo not transmit heat to the fuel in the reservoir. A feed pipe ||8 isanged and Welded to the side |02 as indicated to permit fuel to be addedto the reservoir and this feed pipe is normally closed by a removablecap |20. i A

The combustion chamber |04 is formed within a circular shell |22 spacedconcentrically within the shell |02 to provide a vertical 4portion |2|of the cooling jacket through which coolant may be circulated. Theportion |2| communicates at `|20 and |25 with the region between thebulkheads H4 and ||6 providing for substantially continuous circulationof coolant throughoutthe jacket |05 of the container. The verticalsidepart |2| of the jacket |05 is sealed at the top by an annular ringshaped plate |28 welded in place and provided with a downturned annularlip |30 and a sealing gasket |3| to provide a. tight seal with theremovable top ||0.

The top portion comprises a circular Steel plate |32 to which is securedan upstanding steel ring |34 welded thereto. An outer steel plate |35 isflanged and welded tothe ring |34 as indicated providing within the topa part of the general cooling jacket surrounding the combustion chamber.A hose |38 communicates at |39 with the vertical portion |2| of theycooling jacket and at |40 with the top part insuring completecirculation of coolant over the entire surface of the combustionchamber. Coolant may be admitted to and removed from the system atconvenient points. The top is secured in place on the container by bolts|42 pivotally pinned to flanges |43 of the tank |02.

The mono-fuel, preferably a mixture of nitromethane andtetranitromethane, is transferred from the reservoir |03 to thecombustion chamber |04 by a porous ceramic wick |45 resting on thebottom plate ||2 and passing through a ring or sleeve lll secured toeach of the bulkheads ||4 and H6. The wick is tightly cemented in thesleeve It? to prevent any leakage between the wick and sleeve side wallsfrom the combustion chamber to the reservoir. Liquid fuel is transferredby the porous wick from the reservoir to its upper surface |50 where itis ignited by an igniter |5| and burned to form gas as previouslydescribed in connection with the apparatus of Figures l and 2. As thefuel burns thev pressure in the combustion chamber is increased overthat in the reservoir |03 and this pressure is equalized by means of asleeve |52 that acts as a duct permitting communication between the twoparts of the apparatus. The sleeve |52 is tightly packed with screeningmaterial |53 that operates as a flame check in accordance with thewell-known principle of the Davey safety lamp to prevent flame transferfrom the combustion chamber to the reservoir.

Products of combustion formed in the combustion chamber are removed fromthe apparatus through a sleeve |55 that may be connected to a hose orother container in which the gases are to be received. If desired safetymechanism may be incorporated at this point in the form of a safetyblow-off valve that operates automatically in the event the pressurewithin the combustion chamber becomes excessive. As combustion proceedsthe aqueous product of combustion will condense out as liquid on thewall of the jacket |22 due to the cooling effect of the circulatingcoolant and this condensate will drop down the shell wall and lie in aV- shaped annular trough formed between the shell and an annular ring|58 welded thereto. When the liquid in this trough has accumulated insufficient quantity it may be removed from the system in' exactly thesame manner as described in connection with the tank and the valves andrelated equipment illustrated in Figure 1 and described above. In orderto avoid duplication of description the elements of the apparatus soused are given identical reference characters in Figure 3 as theirsimilar parts that perform the same function have been given in Figure1.

While both forms of the apparatus described herein employ coolingjackets to remove excess heat from the walls of the combustion chamberunder certain conditions this is neither necessary or desirable as forinstance in production of hot gases or steam. In such case insulatingmaterial of any well-known form, such as glass fiber, is tightly packedaround the combustion chamber effectively to insulate its interior fromthe outer surroundings. Thus in either of the constructions describedall of the space occupied by the cooling jacket construction in theside,

end, top and bottom Walls of the combustion chamber is replaced by suchan insulating packing or jacket. This may best be illustrated inconnection with the construction of Figure 3 Where such a modificationwould consist in packing the space between the bulkheads ||4 and 6, thevertical portion |2| of the cooling jacket, and the top portion 0 of thetop thereof with such insulating material as glass wool. The hose |38would be dispensed with. There thus would be provided a complete shellof insulating material surrounding the entire combustion chamber.

From the foregoing description it will be evident that by means of theinvention gas under pressure may be generated by confined combustion offuel and oxidant without the necessity of employing numerous movingparts such as are found in the conventional compressor.

It is intended that the patent shall cover, by suitable expression inthe appended claims, whatever features of patentable novelty reside inthe invention.

I claim:

1. Apparatus for generating gas under pressure comprising an enclosedcombustion chamber. a cooling jacket surrounding said chamber t0 coolthe walls thereof, a burner nozzle discharging into said chamber, anigniter in said chamber adjacent the point o-f discharge of said nozzle,two conduits leading to said nozzle, one for fuel and the other foroxidant, pumps to transmit said fuel and oxidant respectively throughsaid conduits to said nozzle, electrical control valves in said conduitsinterposed between said pumps and said nozzle, a first outlet from saidchamber including a condensate tank, a second outlet from said chamberincluding a pressure responsive device, and electrical connectionsbetween said pressure-responsive device and said valves to operate saidvalves in predetermined manner in accord with pressure changes in saidsecond outlet.

2. Apparatus for generating gas under pres- 7 sure comprising an..enclosed :combustion chain: ber, a cooling jacket surrounding saidchamber to cool the walls thereof, a burner nozzle 111s-,

charging into `said chamber, an igniter in `said chamber adjacent thepoint of discharge of .said nozzle, two conduits leading to said nozzle,ons for .fuel and the' other for oxidant, pumps te transmit said incland oxidant respectively through said conduits `to said nozzle,electrical control valves in ,said conduits interposed 'between said'pumps and said nozzle, an outlet ior removing gaseous rp naolucts .ofcombustion troni said chamber, said outlet including a pressureresponsive device, electrical connections between saidYpressure-responsive device and said valves to 0pcra-.te said valves inpredetermined manner accord with .pressure changes in said outlet, andan outlet for removing 4condensate `from said chamber, .said outletcomprising a ii-rst conduit including a shut 01T valve, a condensatetank connected to said rst conduit, anda second oon? duit including ,eshut ofi valve, whereby to :permit condensate to be drained from saidchamber into said tank and then out of said tank; witnout releasing thepressure therein.

Apparatus for generating gas under pressure comprising ,an enclosed'combustion oneinber, an enclosed reservoir in ,communication therewith,a erst passage connecting A.seid ,reseryoir andsaid combustionchar-aber, ,aiuel :transfer device in said rst passage, asecondpassageonnetting said reservoir and said .combustion charnbar, ,a flame checkin 'said second passage, and, traversed by said passages, a jacketsuricundiiu-Z said combustion chamber.

4- Apparatus far generating ges runder pre1.- sure comprising .enenclosed combustion cnam: ber, an enclosed reservoir in communicationtherewith, lfirst passage connecting said reseiwoir and Sad Combustionfahamber, a .ceramic Wick in said first passage, la second `passageconnect,- ing said `nasen/,oir and seid combustion chamber.,

a name `.angoli in `said second .-pessage, and, traversed vlby saidpassages. a Jacket .surrounding said .combustion chamber- .5- Apparatusier generating gas y.under pressure comprising enclosed kcernbustion,chainber; cooling Jacket surrounding the sides. and ends of saidchamber; c supply system including ltraversi-ng said Jacket fordelivering iual and ,oxidant te said chamber; an igniter *ln proximitythereto, said igniter likewise traversing said Jacket; :aValvcfccntrolied aansluit traversing said jacket for removing gaseousprodnets `ef combustion from said chamber; means communicating t9 saidsupply system deviations pressure the gaseous sraducts 0f combustion.beine reiner/ed, frein said chambers a val-Vaeontrolled conduittraversing said Jacket in the lagttam Portion ci said chamber.: meansfor guldcondensate cOllCGting in said chamber for `discberge into saidiast-rentioned conduit; and, connected .to said lastfmentioned conduit,a condensate tank disposed outside said jacket below the bottoni of saidchanibsr- JOHN a. HANNUM.

REFERENCES oiTED lThe fol-lowing references are of `record in the iileof this Patent:

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